Various types of display devices are known in the art for advertisements, signs, attractions, and the like. Display devices typically have a display area which displays graphics, pictures, characters, words, etc. of interest. Many display devices have an associated illumination means for illuminating the display area for enhancing its visibility in low lighting conditions or to make it more appealing and attention-catching to observers. Some illuminated display devices have certain portions of the display area illuminated more or differently to highlight or direct more attention to those particular portions.
The various types of illumination means known in the art for illuminating display areas of display devices vary in how they illuminate the display area. Some simply comprise a light source, such as a light bulb or a fluorescent light, directing light at the surface of the display area. Others have an at least partially translucent display area with a light source disposed behind it, whereby light from the light source passes through the at least partially translucent display area and illuminates it. Such rear-illuminated display devices, however, have drawbacks. The light source usually projects a strong bright spot, sometimes termed as a hot spot, at the location of the light source behind the display area. Further, there is a gradient of decreasing light in a direction away from the light source on the remainder of the display area. Such inconsistent illumination, particularly the hot spots at the location of the light source, project an unappealing visual impression on an observer and are therefore undesirable.
Solutions that have been proposed for this problem have shortcomings. For example, fiberoptic weaves or meshes disposed under the display area provide inconsistent illumination, and are usually unable to provide an adequate amount of illumination because of the limited amount of light they can carry and deliver. Light bulbs and fluorescent lights usually cause hot spots, and can require large amounts of electric power, usually in the form of alternating current. Therefore, they are not always practicable for use in smaller-sized or battery-powered and portable display devices. Electroluminescent lamps provide illumination proportionate to the amount of electric power provided, so although they may work in battery powered and portable devices, the illumination they provide is limited to the amount of electric power available, which may sometimes not be adequate in a battery operated or portable display device.
Accordingly, there is a need for a display device with a rear-illumination means for its display area that overcomes such problems. The present invention is directed to overcoming one or more of these problems.